Trying to please the famously meticulous quarterback is enough to unnerve any rookie, even one who ran for an NCAA-record 83 touchdowns at Wisconsin.

"He did a great job of calming me down, though, keeping me comfortable, working with me after practice," Ball said. "But I'm still a little nervous, of course. I'm only human."

A jittery Ball failed to win the starting job last year after he whiffed on Seattle middle linebacker Bobby Wagner in the preseason and Manning got squished. Then, after fumbling just twice in 924 carries in college, he matched that total in his first 31 runs in the NFL.

Again, butterflies.

"I was nervous, trying to do too much," Ball said.

That Ball was a bundle of nerves around Manning came as somewhat of a surprise to offensive coordinator Adam Gase.

"You don't usually hear anybody saying anything when they're going through it. Now that we're a year removed, I'm sure he's kind reflects back and says, man, I felt like this. But if he was like that, he hid it pretty good," Gase said Friday. "I just kind of looked at it like he was a rookie and there were a lot of things going on and he just locked up a little bit.

"And I watch him now and I feel like he can just play football now."

Ball finally settled down and by December he had a tight grip on both the football and his role in Denver's record-breaking offense. He finished his rookie year with 559 yards rushing and four TDs.

"The first half I was a little shaky in there," Ball said. "I'm man enough to admit that I was making terrible mistakes early on. But it finally came along. Like they say, better late than never. And I took off from there."

When Knowshon Moreno took his 1,586 all-purpose yards, 14 touchdowns and balky knees to South Beach this offseason, Ball assumed the featured role in the Broncos' backfield.

Money, health and Ball's emergence all played a role in letting Moreno leave even though none of the Broncos' remaining running backs had started an NFL game.

Running backs coach Eric Studesville shrugged off the notion that heading into a Super Bowl-or-else season without any starting experience in the backfield is risky business.

"Oh, the whole starting thing is hard for me, because really the guys that start the game are either on kickoff or kickoff return, you know?" Studesville said. "That's kind of inconsequential to me."

Gase also called it a non-issue, suggesting he could even start bruising tight end Virgil Green, who had a 6-yard run in the playoffs: "I never even think about it. I'll put Virgil out there. These guys are NFL players."

Ball downplayed any concern, too, noting that by last season's end, "it was pretty much 1A and 1B, Knowshon and me."

"We felt good about both of them at the end," Studesville agreed. "We felt like we had two really good backs that we could trust in there at all times, and they were kind of interchangeable."

Joining Ball in the backfield are third-year pro Ronnie Hillman and second-year C.J. Anderson, who have one combined career touchdown run, along with undrafted free agents Juwan Thompson, Brennan Clay and Kapri Bibbs.

This youth movement has forced Studesville to alter his coaching style.

"You can't say this is a veteran guy who's seen this for six years, so he knows what this is. No. We've got to talk about everything from Square 1," Studesville said. "And that makes it fun to go back to the beginning because now you've kind of got to defend all of your techniques and all your philosophies and everything. And it's good for me. It's rejuvenated me as a coach in a lot of ways just because I love going back and teaching the basics."

Notes: LB Von Miller (ACL) is increasing his workload at practice. "My knee is not my issue when I'm out there," he said. "It's just connecting the mind with the body and getting that reaction time down."